In surgical navigation methods (IGS=image-guided surgery), the surgeon regularly needs to assign parts of the body, which for example are arranged symmetrically on different sides of the body, to the corresponding side. A problem exists here, in that a right lower leg bone and a left lower leg bone can for example exhibit a congruent shape and/or view, depending on the position of the observer and/or the perspective from which the bone is observed. This leads to a problem in assigning the corresponding part of the patient's body to the corresponding parts of the body in the model data set of the patient's body which is stored before the operation. In particular, the part of the patient's body can no longer be clearly incorporated into the model data set.
Within this context, a “part of the patient's body” is understood to mean the actual part of the patient's body. The part of the patient's body is to be distinguished from a virtual model of the part of the body which is encompassed by a model data set of the actual part of the patient's body. A part of the patient's body is also referred to here as an anatomical part of the body. The part of the patient's body has hitherto been assigned to a particular region of the body—for example, a shin bone (tibia) has been assigned to the right leg or left leg of the patient—by the surgeon making a manual input into a data processing device. This can however result in errors, which can for example be based on an incorrect input by the user. Inputting also takes time.